1. Field of the Invention
The invention relates to a security arrangement for preventing the unauthorized removal of a lock from the door on which the lock is installed. More specifically, the invention relates to such a security arrangement for use in association with a push button lock arrangement.
2. Description of Prior Art
It is well known that individuals, attempting to make an unauthorized entry through a door which is kept locked by a lock, if they cannot defeat the lock, will attempt to remove the lock to thereby gain entry. It therefore becomes necessary to secure the lock to the door to prevent its unauthorized removal.
Arrangements for preventing the unauthorized removal of cylinder locks are taught in, for example, U.S. Pat. No. 4,484,463, Hennessy, Nov. 27, 1984, U.S. Pat. No. 4,522,048, Davis, Jun. 11, 1985, U.S. Pat. No. 4,453,389, Kaufman, Jun. 12, 1984, U.S. Pat. No. 4,548,062, Kaufman, Oct. 22, 1985, and U.S. Pat. No. 4,712,403, Markisello, Dec. 15, 1987.
In the '463 patent, a plate 12 is mounted on the outside of a door 32 such that aperture 20 overlies cylinder 34. Bolts 42, having heads 44 whose shape corresponds with the shape of the apertures 22 in the plate, secure the plate to the door. Thus, the plate can be removed only from the inside by rotation of the female sleeve nuts 50.
In the '048 patent, a plate 12 is mounted on the outside of the door and a plate 46 is provided on the inside of the door to protect cylinder lock 36 from unauthorized removal. The plate 12 is welded to the tube 16 through which lock 36 passes. The tube 16 and lock 36 extend through bore 34 in door 48. Bolts 54 extend through plate 12, bores 52 (in door 48) and plate 46 and are secured by lock nuts 58 on the inside of the door.
A movable, pivoting plate or blind 6 is provided, in accordance with the teachings of the '389 patent, to protect against unauthorized entry. As seen in FIG. 2 of the patent, plate 6 is urged against connecting bar (tailpiece) 8 by spring 7. If the cylinder is removed, then plate 6 will assume the position shown in dotted lines in FIG. 2 so that a screwdriver cannot be inserted in the slot to unlock the lock. Thus, this arrangement does not prevent removal of the lock, but prevents the lock from being unlocked after the cylinder has been removed. Nevertheless, it is of interest in that it teaches the use of a plate 6 for preventing unauthorized entry.
In the '062 patent, a plate 1 is mounted over lock 2 on the inside of the door to prevent the lock from being pushed in from the outside. Plate 9 may be mounted on the outside of the door to cover the heads of bolts 4 which fasten plate 1 to the door (see FIG. 3).
Plate 3, in the '403 patent, includes an opening having a large hole 2 and a smaller hole underlying the hole 2 (see FIG. 6). As seen in FIGS. 1 to 4, the cylinder is slid into the large hole and the plate is then moved up (or the cylinder moved down) so that the arrangement is securely held in the plate. The arrangement is then mounted on a door as shown in FIG. 4 of the patent.
In all of the above arrangements, authorized removal of the lock is possible when the lock is either in its locked or unlocked condition.
Also known in the art are arrangements for securing push button lock arrangements to the doors on which they are installed. To Applicant's knowledge, all such arrangements permit authorized removal of the lock from the door even when the correct combination has not been punched in.